Layered structures, production methods thereof, and liquid crystal display including the same

ABSTRACT

A layered structure including a transparent substrate; a photoluminescent layer disposed on the transparent substrate and a pattern of a quantum dot polymer composite; and a capping layer disposed on the photoluminescent layer and including an inorganic material, a method of producing the same, a liquid crystal display including the same. The quantum dot polymer composite includes a polymer matrix; and a plurality of quantum dots in the polymer matrix, the pattern of the quantum dot polymer composite includes at least one repeating section and the repeating section includes a first section configured to emit light of a first peak wavelength, the inorganic material is disposed on at least a portion of a surface of the repeating section, and the inorganic material includes a metal oxide, a metal nitride, a metal oxynitride, a metal sulfide, or a combination thereof.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application that claims priority to U.S.application Ser. No. 15/849,994 filed Dec. 21, 2017, now U.S. Pat. No.11,099,410, which in turn claims priority to Korean Patent ApplicationNo. 10-2016-0175980 filed in the Korean Intellectual Property Office onDec. 21, 2016, and all the benefits accruing therefrom under 35 U.S.C.§§ 119; 120, the contents of which are incorporated herein by referencein their entirety.

BACKGROUND 1. Field

Layered structures, production methods thereof, and liquid crystaldisplays including the same are disclosed.

2. Description of the Related Art

A liquid crystal display (“LCD”) that is one of a flat panel displaydevice may include a liquid crystal panel including two substrates(e.g., a lower substrate and an upper substrate) on which a pixelelectrode and a common electrode are formed, and a liquid crystal layerdisposed therebetween. The lower (array) substrate may have a pluralityof gate wires and data wires defining a pixel area, and may include athin film transistor at a crossing point of two wires that may beconnected with a pixel electrode of each pixel area. The upper substratemay include a color filter layer that includes patterned (red, green,and blue) absorption-type color filter sections corresponding to thepixel area. The liquid crystal display may include an optical element(e.g., polarizer) on, under and/or inside a liquid crystal panel.

SUMMARY

An embodiment provides a layered structure capable of providing a liquidcrystal display having improved luminous efficiency.

An embodiment provides a method of producing the layered structure.

An embodiment provides a liquid crystal display including the layeredstructure.

In an embodiment, a layered structure includes

-   -   a photoluminescent layer including a pattern of a quantum dot        polymer composite; and    -   a capping layer being disposed on the photoluminescent layer and        including an inorganic material,    -   wherein the quantum dot polymer composite includes a polymer        matrix; and a plurality of quantum dots in the polymer matrix,    -   wherein the pattern of the quantum dot polymer composite        includes a repeating section and wherein the repeating section        includes a first section configured to emit light of a first        peak wavelength,    -   wherein the inorganic material is disposed on at least a portion        of a surface of the repeating section, and    -   wherein the inorganic material includes a metal oxide, a metal        nitride, a metal oxynitride, a metal sulfide, or a combination        thereof.

The layered structure further includes a substrate (e.g., a transparentsubstrate) disposed on a surface of the photoluminescent layer oppositeto the capping layer.

The polymer matrix may include a cross-linked polymer and a linearpolymer having a carboxylic acid group-containing repeating unit.

The cross-linked polymer may include a thiol-ene resin, a cross-linkedpoly(meth)acrylate, a cross-linked polyurethane, a cross-linked epoxyresin, a cross-linked vinyl polymer, a cross-linked silicone resin, or acombination thereof.

The carboxylic acid group-containing repeating unit of the linearpolymer may include a unit derived from a monomer including a carboxylicacid group and a carbon-carbon double bond, a unit derived from amonomer having a dianhydride moiety, or a combination thereof.

The quantum dot may include a Group II-VI compound, a Group III-Vcompound, a Group IV-VI compound, a Group IV element or compound, aGroup I-III-VI compound, a Group I-II-IV-VI compound, or a combinationthereof.

In some embodiments, the quantum dot does not include cadmium.

The quantum dot may have a core-shell structure.

The quantum dot may include an organic ligand on a surface of thequantum dot.

The organic ligand may include RCOOH, RNH₂, R₂NH, R₃N, RSH, R₃PO, R₃P,ROH, RCOOR′, RPO(OH)₂, R₂POOH, wherein, R and R are each independently aC5 to C24 substituted or unsubstituted aliphatic hydrocarbon group or aC6 to C20 substituted or unsubstituted aromatic hydrocarbon group,polymer organic ligand, or a combination thereof.

The repeating section may further include a second section configured toemit light of a second peak wavelength that is different from the firstpeak wavelength.

The repeating section may further include a third section configured toemit or transmit light of a third peak wavelength that is different fromthe first peak wavelength and the second peak wavelength.

The first peak wavelength (i.e., the first maximum peak emissionwavelength) may be greater than about 580 nanometers and less than orequal to about 680 nanometers.

The second peak wavelength may be greater than about 480 nanometers andless than or equal to about 580 nanometers.

The third peak wavelength may be greater than or equal to about 380nanometers and less than or equal to about 480 nanometers.

At least a portion of the surface of the repeating section may include(e.g., be coated with) a coating including the inorganic material. Theinorganic material may have a refractive index of about 1.4 to about 3.

The inorganic material may include a silicon oxide, a silicon nitride, asilicon oxynitride, a hafnium oxide, a tantalum oxide, a titanium oxide,a zirconium oxide, a zinc oxide, a zinc sulfide, a magnesium oxide, acesium oxide, a lanthanum oxide, an indium oxide, a niobium oxide, analuminum oxide, or a combination thereof.

The capping layer may include a continuous (deposition) film of theinorganic material.

The capping layer may include at least two layers of the inorganicmaterial, wherein at least two adjacent layers optionally have adifferent composition of an inorganic material, a different thickness, adifferent refractive index, a different transmittance, or a combinationthereof.

The capping layer may include a first layer including a first inorganicmaterial and having a first refractive index and a second layerincluding a second inorganic material and having a second refractiveindex, wherein the second layer is directly adjacent (or contacts) thefirst layer and a difference between the second refractive index and thefirst refractive index is at least about 0.5 (e.g., the secondrefractive index is at least about 0.5 less than the first refractiveindex).

The capping layer may include the first layer and the second layerdisposed alternately.

A thickness of the first layer may be from about 3 nanometers to about300 nanometers and a thickness of the second layer may be from about 3nanometers to about 300 nanometers.

The thickness of the first layer may be greater than the thickness ofthe second layer.

The thickness of the first layer may be smaller than the thickness ofthe second layer.

The first inorganic material may have a lower refractive index than thesecond inorganic material and the first inorganic material may include asilicon oxide.

The second inorganic material may include a hafnium oxide, a tantalumoxide, a titanium oxide, a zirconium oxide, a magnesium oxide, a cesiumoxide, a lanthanum oxide, an indium oxide, a niobium oxide, an aluminumoxide, a silicon nitride, or a combination thereof.

A thickness of the capping layer may be greater than or equal to about100 nanometers and less than or equal to about 3000 nanometers.

The capping layer may have a transmittance of greater than or equal toabout 90% for light having a wavelength of about 380 nanometers to about520 nanometers.

The layered structure may further include an overcoat including anorganic polymer, wherein the overcoat is on the capping layer.

In an embodiment, a method of producing the layered structure includes

-   -   applying a composition including a plurality of quantum dots, a        photopolymerizable monomer including at least two polymerizable        moieties, a linear polymer comprising a carboxylic acid        group-containing repeating unit (e.g., a carboxylic acid linear        polymer), a photoinitiator, and an organic solvent, on a        transparent substrate to form a film;    -   exposing a predetermined region of the formed film to light        (e.g., having a wavelength of less than about 410 nm) to        polymerize and cross-link in the exposed predetermined region        and to form a quantum dot polymer composite dispersed in a        polymer matrix;    -   removing an unexposed region from the film using an alkali        aqueous solution to obtain a quantum dot-polymer composite        pattern;    -   forming a capping layer including an inorganic material on the        quantum dot-polymer composite pattern; and    -   heating the quantum dot-polymer composite pattern at a        temperature of greater than or equal to about 160° C. after        forming the capping layer including the inorganic material.

The light may have a wavelength of less than about 410 nanometers.

The method may further include heating the exposed predetermined regionat a temperature of greater than or equal to (the organic solvent'sboiling point—10° C.) and less than about 160° C. before forming thecapping layer.

In the method, the series of the processes may be repeated at leasttwice.

The forming of the capping layer including the inorganic material may beperformed by physical vapor deposition, chemical vapor deposition, or acombination thereof.

In an embodiment, a liquid crystal display includes

-   -   a liquid crystal panel including a lower substrate, an upper        substrate, a liquid crystal layer disposed between the upper and        lower substrates, and the aforementioned layered structure used        or included as a photoluminescent color filter layer provided on        the upper substrate;    -   a polarizer disposed under the lower substrate; and    -   a backlight unit disposed under the polarizer and emitting blue        light.

The liquid crystal display may further include an optical elementbetween the photoluminescent color filter layer and the liquid crystallayer.

The optical element may include at least one of a polarizer and acoating that controls a refractive index without a polarizationfunction.

In the liquid crystal display, the repeating section may furthercomprise a second section configured to emit light of a second peakwavelength that is different from the first peak wavelength.

The liquid crystal display may further include a blue light blockingelement (e.g., a blue cut filter) disposed (e.g., on a regioncorresponding to the first and/or second section(s)) on the repeatingsection.

In case of environmentally-friendly cadmium-free quantum dots, ligandsof the quantum dots may be detached by oxidation or heat even in arelatively low temperature thermal process of less than or equal toabout 200° C. and thus luminous efficiency may be sharply decreased andbrightness thereof may decrease during the production of a displaydevice. According to an embodiment, it may be possible to improveluminous efficiency that may be otherwise deteriorated by such a thermalprocess and to prevent deterioration of light characteristics of quantumdots at a relatively high temperature of about 180° C. to about 230° C.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages and features of this disclosure willbecome more apparent by describing in further detail exemplaryembodiments thereof with reference to the accompanying drawings, inwhich:

FIG. 1 is a schematic view showing an embodiment of a cross-section of alayered structure;

FIG. 2 is a schematic view showing an embodiment of a cross-section of alayered structure;

FIG. 3 is a schematic view showing an embodiment of a cross-section of amulti-layered capping layer in a layered structure;

FIG. 4 is a view showing an embodiment of a process of forming aphotoluminescent layer including a quantum dot-polymer composite patternon a substrate In a layered structure;

FIG. 5 is a cross-sectional view showing an embodiment of a liquidcrystal display;

FIG. 6 is a graph showing changes of a blue photoconversion efficiencyof the layered structure during a production process of the layeredstructure according to Example 3 and Comparative Example 3; and

FIG. 7 is a graph showing changes of a blue photoconversion efficiencyof the layered structure during a production process of the layeredstructure according to Example 4 and Comparative Example 4.

DETAILED DESCRIPTION

Advantages and characteristics of this disclosure, and a method forachieving the same, will become evident referring to the followingexample embodiments together with the drawings attached hereto. Theembodiments, may, however, be embodied in many different forms andshould not be construed as being limited to the embodiments set forthherein. If not defined otherwise, all terms (including technical andscientific terms) in the specification may be defined as commonlyunderstood by one skilled in the art. The terms defined in agenerally-used dictionary may not be interpreted ideally orexaggeratedly unless dearly defined. In addition, unless explicitlydescribed to the contrary, the word “comprise” and variations such as“comprises” or “comprising” will be understood to imply the inclusion ofstated elements but not the exclusion of any other elements.

Further, the singular includes the plural unless mentioned otherwise.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification.

It will be understood that when an element such as a layer, film,region, or substrate is referred to as being “on” another element, itcan be directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” another element, there are no intervening elements present.

It will be understood that, although the terms “first,” “second,”“third,” etc. may be used herein to describe various elements,components, regions, layers, and/or sections, these elements,components, regions, layers, and/or sections should not be limited bythese terms. These terms are only used to distinguish one element,component, region, layer, or section from another element, component,region, layer or section. Thus, “a first element,” “component,”“region,” “layer” or “section” discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms, including “at least one,” unless the context clearly indicatesotherwise. “At least one” is not to be construed as being limited to “a”or “an.” “Or” means “and/or.” As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system).

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

As used herein, the term “hydrophobic moiety” refers to a moietyproviding the corresponding compound with a tendency to be agglomeratedin an aqueous solution and to repel water. For example, the hydrophobicmoiety may include an aliphatic hydrocarbon group having a carbon numberof 1 or greater (at least two) (alkyl, alkenyl, alkynyl, etc.), anaromatic hydrocarbon group having a carbon number of 6 or greater(phenyl, naphthyl, aralkyl group, etc.), or an alicyclic hydrocarbongroup having a carbon number of 5 or greater. The hydrophobic moiety isnot mixed with the ambient medium since it is substantially lacking ofcapability of making a hydrogen bond with the ambient medium, or sincethe polarity thereof is not matched with that of the ambient medium.

As used herein, the term “visible light” refers to light having awavelength of about 390 nanometers (nm) to about 700 nm. As used herein,the term ultraviolet (“UV”) may refer to light having a wavelength ofgreater than or equal to about 200 nm and less than about 390 nm.

As used herein, a (blue) photoconversion efficiency refers to a ratio ofemission light relative to incident light (e.g., blue light). Forexample, a blue photoconversion efficiency is a ratio of a lightemission dose of a quantum dot polymer composite relative to absorbedlight dose of the quantum dot polymer composite from excited light(i.e., blue light). The total light dose (B) of excited light may beobtained by integrating its PL spectrum, the PL spectrum of the quantumdot polymer composite film is measured, a dose (A) of light in a greenor red wavelength region emitted from the quantum dot polymer compositefilm and a dose (B′) of blue light may be obtained, and a bluephotoconversion efficiency may be obtained by the following equation:A/(B−B′)×100%=photoconversion efficiency (%)

As used herein, the term “dispersion” refers to dispersion wherein adispersed phase includes a solid and a continuous medium includesliquid. As used herein, “dispersion” may refer to colloidal dispersionwherein dispersion or dispersed phase has a dimension of about 1 nm toabout 1 micrometer (μm).

As used herein, “Group” refers to a Group of Periodic Table.

As used herein, “Group II” refers to Group IIA and a Group IIB, andexamples of the Group II metal may include Cd, Zn, Hg, and Mg, but arenot limited thereto.

“Group III” refers to a Group IIIA and a Group IIIB, and examples of theGroup III metal may include Al, In, Ga, and TI, but are not limitedthereto.

“Group IV” refers to a Group IVA and a Group IVB, and examples of theGroup IV metal may include Si, Ge, and Sn but are not limited thereto.As used herein, the term “a metal” may include a semi-metal such as Si.

“Group I” refers to a Group IA and a Group IB, and may include Li, Na,K, Rb, and Cs but are not limited thereto.

“Group V” refers to Group VA and may include nitrogen, phosphorus,arsenic, antimony, and bismuth but is not limited thereto.

“Group VI” refers to Group VIA and may include sulfur, selenium, andtellurium, but is not limited thereto.

“Substituted” means that the compound or group is substituted with atleast one (e.g., 1, 2, 3, or 4) substituent independently selected froma hydroxyl (—OH), a C1-9 alkoxy, a C1-9 haloalkoxy, an oxo (═O), a nitro(—NO₂), a cyano (—CN), an amino (—NH2), an azido (—N3), an amidino(—C(═NH)NH2), a hydrazino (—NHNH2), a hydrazono (═N—NH2), a carbonyl(—C(═O)—), a carbamoyl group (—C(O)NH2), a sulfonyl (—S(═O)2-), a thiol(—SH), a thiocyano (—SCN), a tosyl (CH3C6H4SO2-), a carboxylic acid(—C(═O)OH), a carboxylic C1 to C6 alkyl ester (—C(═O)OR wherein R is aC1 to C6 alkyl group), a carboxylic acid salt (—C(═O)OM) wherein M is anorganic or inorganic cation, a sulfonic acid (—SO3H2), a sulfonic mono-or dibasic salt (—SO3MH or —SO3M2 wherein M is an organic or inorganiccation), a phosphoric acid (—PO3H2), a phosphoric acid mono- or dibasicsalt (—PO3MH or —PO3M2 wherein M is an organic or inorganic cation), aC1 to C12 alkyl, a C3 to C12 cycloalkyl, a C2 to C12 alkenyl, a C5 toC12 cycloalkenyl, a C2 to C12 alkynyl, a C6 to C12 aryl, a C7 to C13arylalkylene, a C4 to C12 heterocycloalkyl, and a C3 to C12 heteroarylinstead of hydrogen, provided that the substituted atom's normal valenceis not exceeded.

A liquid crystal display may have decreased luminous efficiency forexample by a color filter layer and accordingly technologies forimproving luminous efficiency of a liquid crystal display are desired.

In an embodiment, a layered structure includes a photoluminescent layerhaving a pattern of a quantum dot polymer composite; and a capping layerdisposed on the photoluminescent layer and including an inorganicmaterial. The layered structure further includes a substrate (e.g., atransparent substrate), on which the photoluminescent layer is disposed.The quantum dot polymer composite includes a plurality of quantum dotsdispersed in a polymer matrix and the pattern of the quantum dot polymercomposite includes at least one repeating section, and the repeatingsection includes a first section configured to emit light of a firstpeak wavelength. The repeating section may further include a secondsection configured to emit light of a second peak wavelength that isdifferent from the first peak wavelength. The repeating section mayfurther include a third section configured to emit or transmit light ofa third peak wavelength that is different from the first peak wavelengthand the second peak wavelength. For example, the first peak wavelength(e.g. maximum light emitting peak wavelength) may be from about 580 nmto about 650 nm (e.g., about 620 nm to about 650 nm). The first sectionmay be an R section to emit red light, but is not limited thereto. Thesecond peak wavelength (e.g. maximum light emitting peak wavelength) maybe from about 480 nm to about 580 nm (e.g., about 500 nm to about 560nm). The second section may be a G section to emit green light, but isnot limited thereto. The third peak wavelength (e.g. maximum lightemitting peak wavelength) may be from about 380 nm to about 480 nm(e.g., about 440 nm to about 480 nm). The third section mayemit/transmit blue light, but is not limited thereto.

The inorganic material may be disposed on at least a portion of asurface of the repeating section. The inorganic material may include ametal oxide, a metal nitride, a metal oxynitride, a metal sulfide, or acombination thereof.

The (transparent) substrate may be a substrate including an insulationmaterial. The substrate may include glass; various polymer (e.g.,polyester such as polyethylene terephthalate (“PET”) and polyethylenenaphthalate (“PEN”), poly(meth)acrylate, polycarbonate, polyimide,polyimide-amide, or the like); polysiloxane (e.g. polydimethylsiloxane(“PDMS”)); an inorganic material such as Al₂O₃ or ZnO; or a combinationthereof, but is not limited thereto. Herein, the term “transparent”refers to light transmittance of greater than or equal to about 85%, forexample, greater than or equal to about 88%, greater than or equal toabout 90%, greater than or equal to about 95%, greater than or equal toabout 97%, or greater than or equal to about 99% for light having apredetermined wavelength. The predetermined wavelength may be from about380 nm to about 780 nm. The predetermined wavelength may be determinedconsidering the light emitted from each of the sections (e.g., red,green or blue light). A thickness of the (transparent) substrate may beappropriately selected considering a substrate material but is notparticularly limited. The substrate may have flexibility.

The photoluminescent layer disposed on the transparent substrateincludes a pattern of a quantum dot polymer composite including aplurality of quantum dots dispersed in a polymer matrix.

The polymer matrix may include a cross-linked polymer; and linearpolymer having a carboxylic acid group-containing repeating unit. Thecross-linked polymer may be a polymer cross-linked by light.

The cross-linked polymer may include a thiol-ene resin, a cross-linkedpoly(meth)acrylate, a cross-linked polyurethane, a cross-linked epoxyresin, a cross-linked vinyl polymer, a cross-linked silicone resin, or acombination thereof. The cross-linked polymer may be a copolymer. Thecross-linked polymer may be a polymerization product of aphotopolymerizable compound (e.g., a monomer or an oligomer) having oneor more, for example, two, three, four, five, six, or morephotopolymerizable functional groups (e.g., carbon-carbon double bondssuch as (meth)acrylate groups or vinyl groups, epoxy groups, etc.). Thephotopolymerizable compound may be a generally-used photopolymerizablemonomer or oligomer in a photosensitive resin composition.

In an embodiment, the photopolymerizable compound may include anethylenic unsaturated monomer such as a (meth) acrylate monomer or avinyl monomer; a reactive oligomer having two or more photopolymerizablemoieties (e.g., ethylene oligomer, alkylene oxide oligomer, or the likehaving epoxy groups, vinyl groups, etc.); a copolymer of the reactiveoligomer and the ethylenic unsaturated monomer; a urethane oligomerhaving two or more photopolymerizable moieties (e.g., (meth)acrylatemoieties); a siloxane oligomer having two or more photopolymerizablemoieties; or a combination thereof. The photopolymerizable compound mayfurther include a thiol compound having at least two thiol groups atterminal ends. The photopolymerizable compound may be commerciallyavailable or may be synthesized by a known method. The cross-linkedpolymer may be a polymerization product of a mixture including thephotopolymerizable compound.

The (meth)acrylate monomer may include a monofunctional ormulti-functional ester of (meth)acrylic acid having at least onecarbon-carbon double bond. The (meth)acrylate monomer may include adi(meth)acrylate compound, a tri(meth)acrylate compound, atetra(meth)acrylate compound, a penta(meth)acrylate compound, ahexa(meth)acrylate compound, or a combination thereof. Examples of the(meth)acrylate monomer may be alkyl(meth)acrylate, ethyleneglycoldi(meth)acrylate, triethylene glycoldi(meth)acrylate, diethyleneglycoldi(meth)acrylate, 1,4-butanedioldi(meth)acrylate,1,6-hexanedioldi(meth)acrylate, neopentylglycoldi(meth)acrylate,pentaerythritoldi(meth)acrylate, pentaerythritoitri(meth)acrylate,pentaerythritoltetra(meth)acrylate, dipentaerythritoldi(meth)acrylate,dipentaerythritoltri(meth)acrylate,dipentaerythrdtolpenta(meth)acrylate,dipentaerythritolhexa(meth)acrylate, bisphenol A epoxyacrylate,bisphenol A di(meth)acrylate, trimethylolpropanetri(meth)acrylate,novolac epoxy (meth)acrylate, ethyleneglycolmonomethylether(meth)acrylate, tris(meth)acryloyloxyethyl phosphate,diethylene glycoldi(meth)acrylate, triethylene glycoldi(meth)acrylate,or propylene glycoldi(meth)acrylate, but are not limited thereto.

The thiol compound having at least two thiol groups at terminal ends maybe a compound represented by Chemical Formula 1:

-   -   wherein, in the chemical formula, R¹ is hydrogen; a substituted        or unsubstituted C1 to C30 linear or branched alkyl group; a        substituted or unsubstituted C6 to C30 aryl group; a substituted        or unsubstituted C3 to C30 heteroaryl group; a substituted or        unsubstituted C3 to C30 cycloalkyl group; a substituted or        unsubstituted C2 to C30 heterocycloalkyl group; a C1 to C10        alkoxy group; a hydroxy group; —NH₂; a substituted or        unsubstituted C1 to C30 amine group (—NRR′, wherein R and R′ are        independently hydrogen or a C1 to C30 linear or branched alkyl        group, provided that R and R′ are not hydrogen simultaneously);        an isocyanate group; a halogen; —ROR′ (wherein R is a        substituted or unsubstituted C1 to C20 alkylene group and R′ is        hydrogen or a C1 to C20 linear or branched alkyl group); an acyl        halide (—RC(═O)X, wherein R is a substituted or unsubstituted        alkylene group and X is a halogen); —C(═O)OR′ (wherein R′ is        hydrogen or a C1 to C20 linear or branched alkyl group); —CN;        C(═O)NRR′ (wherein R and R′ are independently hydrogen or a C1        to C20 linear or branched alkyl group);or —C(═O)ONRR′ (wherein R        and R′ are independently hydrogen or a C1 to C20 linear or        branched alkyl group),    -   L₁ is a carbon atom, a substituted or unsubstituted C1 to C30        alkylene moiety, a substituted or unsubstituted C3 to C30        cycloalkylene moiety, a substituted or unsubstituted C6 to C30        arylene moiety, or a substituted or unsubstituted C3 to C30        heteroarylene moiety wherein at least one methylene (—CH₂—) of        the substituted or unsubstituted C1 to C30 alkylene group may be        replaced by sulfonyl (—SO₂—), carbonyl (CO), ether (—O—),        sulfide (—S—), sulfoxide (—SO—), ester (—C(═O)O—), amide        (—C(═O)NR—) (wherein R is hydrogen or a C1 to C10 alkyl group)        or a combination thereof,    -   Y₁ is a single bond; a substituted or unsubstituted C1 to C30        alkylene group; a substituted or unsubstituted C2 to C30        alkenylene group; or a C2 to C30 alkylene group or a C3 to C30        alkenylene group wherein at least one methylene (—CH₂—) is        replaced by a sulfonyl (—S(═O)₂—), a carbonyl (—C(═O)—), an        ether (—O—), a sulfide (—S—), a sulfoxide (—S(═O)—), an ester        (—C(═O)O—), an amide (—C(═O)NR—) (wherein R is hydrogen or a C1        to C10 linear or branched alkyl group), an imine (—NR—) (wherein        R is hydrogen or a C1 to C10 linear or branched alkyl group), or        a combination thereof,    -   m is an integer of 1 or more,    -   k1 is 0 or an integer of 1 or more, k2 is an integer of 1 or        more, and    -   the sum of m and k2 is an integer of 3 or more,    -   provided that when Y₁ is not a single bond, m does not exceed        the valence of Y₁ and    -   provided that the sum of k1 and k2 does not exceed the valence        of L₁.

The thiol compound may include a compound represented by ChemicalFormula 1-1:

-   -   wherein, in the chemical formula, L₁′ is carbon, a substituted        or unsubstituted C2 to C20 alkylene moiety, a substituted or        unsubstituted C6 to C30 arylene moiety; a substituted or        unsubstituted C3 to C30 heteroarylene moiety; a substituted or        unsubstituted C3 to C30 cycloalkylene moiety; or a substituted        or unsubstituted C2 to C30 heterocycloalkylene moiety,    -   each of Y_(a) to Y_(d) is independently a direct bond; a        substituted or unsubstituted C1 to C30 alkylene group; a        substituted or unsubstituted C2 to C30 alkenylene group; or a C2        to C30 alkylene group or a C3 to C30 alkenylene group wherein at        least one methylene (—CH₂—) is replaced by an sulfonyl        (—S(═O)₂—), a carbonyl (—C(═O)—), an ether (—O—), a sulfide        (—S—), a sulfoxide (—S(═O)—), an ester (—C(═O)O—), an amide        (—C(═O)NR—) (wherein R is hydrogen or a C1 to C10 linear or        branched alkyl group), an imine (—NR—) (wherein R is hydrogen or        a C1 to C10 linear or branched alkyl group), or a combination        thereof, and    -   each of R_(a) to R_(d) is independently R¹ of Chemical Formula 1        or SH, provided that at least two of R_(a) to R_(d) are SH.

The thiol compound may be a dithiol compound, a trithiol compound, atetrathiol compound, or a combination thereof. For example, thethiolcompound may be glycol di-3-mercaptopropionate, glycol dimercaptoacetate, trimethylol propane tris(3-mercaptopropionate), pentaerythritoltetrakis(3-mercaptopropionate), pentaerythritoltetrakis(2-mercaptoacetate), 1,6-hexanedithiol, 1,3-propanedithiol,1,2-ethanedithiol, polyethylene glycol dithiol including 1 to 10ethylene glycol repeating units, or a combination thereof. A reactionbetween the thiol compound and the ethylenic unsaturated monomer mayprovide a thiol-ene resin.

The linear polymer having a carboxylic acid group-containing repeatingunit (hereinafter, also referred to as a carboxylic acid polymer or abinder) may be a copolymer of monomer mixture of a first monomerincluding a carboxylic acid group and a carbon-carbon double bond, asecond monomer including a carbon-carbon double bond and a hydrophobicmoiety and not including a carboxylic acid group, and optionally a thirdmonomer including a carbon-carbon double bond and a hydrophilic moietyand not including a carboxylic acid group;

-   -   a multiple aromatic ring-containing polymer having a backbone        structure where two aromatic rings are bound to a quaternary        carbon atom that is a constituent atom of another cyclic moiety        in the main chain and including a carboxylic acid group (—COOH);        or    -   a combination thereof.

The carboxylic acid group-containing repeating unit may be derived forma monomer including a carboxylcacid group and a carbon-carbon doublebond, a monomer having a dianhydride moiety, or a combination thereof.

Examples of the first monomer may include carboxylic acid vinyl estercompounds such as acrylic acid, methacrylic acid, maleic acid, itaconicacid, fumaric acid, 3-butenoic acid, vinyl acetate, or vinyl benzoate,but are not limited thereto. The first monomer may be at least onecompound. Examples of the second monomer may be an alkenyl aromaticcompound such as styrene, α-methyl styrene, vinyl toluene, or vinylbenzyl methyl ether, an unsaturated carboxylic acid ester compound suchas methyl acrylate, methyl methacrylate, ethyl acrylate, ethylmethacrylate, butyl acrylate, butyl methacrylate, benzyl acrylate,benzyl methacrylate, cyclohexyl acrylate, cycohexyl methacrylate, phenylacrylate, or phenyl methacrylate; unsaturated carboxylic acid aminoalkyl ester compound such as 2-amino ethyl acrylate, 2-amino ethylmethacrylate, 2-dimethyl amino ethyl acrylate, or 2-dimethyl amino ethylmethacrylate; unsaturated imide compound such as N-phenylmaleimide,N-benzylmaleimide, or N-alkylmaleimide; an unsaturated carboxylic acidglycidyl ester compound such as glycidyl acrylate or glycidylmethacrylate; a vinyl cyanide compound such as acrylonitrile,methacrylonitrile; or an unsaturated amide compound such as acryl amideor methacryl amide, but are not limited thereto. As the second monomer,at least one compound may be used. Examples of the third monomer mayinclude 2-hydroxy ethyl acrylate, 2-hydroxy ethyl methacrylate,2-hydroxy butyl acrylate, or 2-hydroxy butyl methacrylate, but are notlimited thereto. As the third monomer, at least one compound may beused.

The copolymer may include a first repeating unit derived from the firstmonomer, a second repeating unit derived from the second monomer, andoptionally a third repeating unit derived from the third monomer. In thecopolymer, a content of the first repeating unit may be greater than orequal to about 10 mol %, for example, greater than or equal to about 15mol %, greater than or equal to about 25 mol %, or greater than or equalto about 35 mol %. In the carboxylic acid polymer, a content of thefirst repeating unit may be less than or equal to about 90 mol %, forexample, less than or equal to about 89 mol %, less than or equal toabout 80 mol %, less than or equal to about 70 mol %, less than or equalto about 60 mol %, less than or equal to about 50 mol %, less than orequal to about 40 mol %, less than or equal to about 35 mol %, or lessthan or equal to about 25 mol %.

In the copolymer, a content of the second repeating unit may be greaterthan or equal to about 10 mol %, for example, greater than or equal toabout 15 mol %, greater than or equal to about 25 mol %, or greater thanor equal to about mol %. In the binder polymer, a content of the secondrepeating unit may be less than or equal to about 90 mol %, for example,less than or equal to about 89 mol %, less than or equal to about 80 mol%, less than or equal to about 70 mol %, less than or equal to about 60mol %, less than or equal to about 50 mol %, less than or equal to about40 mol %, less than or equal to about 35 mol %, or less than or equal toabout 25 mol %.

In the copolymer, if it is present, a content of the third repeatingunit may be greater than or equal to about 1 mol %, for example, greaterthan or equal to about 5 mol %, greater than or equal to about 10 mol %,or greater than or equal to about 15 mol %. In the binder polymer, acontent of the third repeating unit may be less than or equal to about20 mol %, for example, less than or equal to about 15 mol %, or lessthan or equal to about 10 mol %.

The copolymer may be a copolymer of (meth)acrylic acid and; at least onesecond/third monomer including arylalkyl(meth)acrylate, hydroxyalkyl(meth)acrylate, and styrene. For example, the binder polymer may be amethacrylic acid/methyl methacrylate copolymer, a methacrylicacid/benzyl methacrylate copolymer, a methacrylic acid/benzylmethacrylate/styrene copolymer, a methacrylic acibenzylmethacrylate/2-hydroxy ethyl methacrylate copolymer, or a methacrylicacidbenzyl methacrylate/styrene/2-hydroxy ethyl methacrylate copolymer.

The carboxylic acid polymer may include a multiple aromaticring-containing polymer. The multiple aromatic ring-containing polymerhas a backbone structure where two aromatic rings are bound to aquaternary carbon atom that is a constituent atom of another cyclicmoiety in the main chain (e.g., being bound to the main chain) andincludes a carboxylic acid group (—COOH).

In the multiple aromatic ring-containing polymer, the backbone structuremay be represented by Chemical Formula A:

-   -   wherein, * is a portion that is linked to an adjacent atom of        the main chain of the binder, and Z₁ is a linking moiety        represented by any one of Chemical Formulae A-1 to A-6, and in        Chemical Formulae A-1 to A-6, * is a portion that is linked to        an aromatic moiety:

-   -   wherein, R^(a) is a hydrogen, an ethyl group, C₂H₄Cl, C₂H₄OH,        CH₂CH═CH₂, or a phenyl group,

The multiple aromatic ring-containing polymer may include a repeatingunit represented by Chemical Formula B:

-   -   wherein Z¹ is a linking moiety represented by any one of        Chemical Formulae A-1 to A-8,    -   L is a direct bond, a C1 to C10 alkylene, a C1 to C10 alkylene        having a substituent including a carbon-carbon double bond, a C1        to C10 oxy alkylene, or a C1 to C10 oxy alkylene having a        substituent including a carbon-carbon double bond,    -   A is —NH—, —O—, or a C1 to C10 alkylene, and    -   Z² is a C6 to C40 aromatic organic group.    -   each of R¹ and R² is independently hydrogen, a halogen, or a        substituted or unsubstituted C1 to C20 alkyl group,    -   m1 and m2 are independently an integer ranging from 0 to 4.    -   In Chemical Formula B, Z² may be any one of Chemical Formula        [B-1], Chemical Formula [B-2] and Chemical Formula [B-3]:

-   -   wherein * is a portion that is linked to an adjacent carbonyl        carbon, Chemical Formula B-2

-   -   wherein * is a portion that is linked to an adjacent carbonyl        carbon,

-   -   wherein * is a portion that is linked to an adjacent carbonyl        carbon, L is a direct bond, —O—, —S—, —C(═O)—, —CH(OH)—,        —S(═O)₂—, —Si(CH₃)₂—, (CH₂)p (wherein 1≤p≤10), (CF₂)_(q)        (wherein 1≤q≤10), —CR₂— (wherein R is independently hydrogen, a        C1 to C10 aliphatic hydrocarbon group, a C6 to C20 aromatic        hydrocarbon group, or a C6 to C20 alicyclic hydrocarbon group),        —C(CF₃)₂—, —C(CF₃)(C₆H₅)—, or —C(═O)NH—.

The multiple aromatic ring-containing polymer may include a structuralunit represented by Chemical Formula C:

-   -   wherein each of R¹ and R² is independently hydrogen or a        substituted or unsubstituted (meth)acryloyloxyalkyl group,    -   each of R³ and R⁴ is independently hydrogen, a halogen, or a        substituted or unsubstituted C1 to C20 alkyl group,    -   Z¹ is a linking moiety represented by Chemical Formulae A-1 to        A-6,    -   Z² is an C6 to C40 aromatic organic group such as the moieties        set forth above, and    -   m1 and m2 are independently an integer ranging from 0 to 4.

In an embodiment, the multiple aromatic ring-containing polymer may bean acid adduct of bisphenol fluorene epoxy acrylate. For example, thebisphenol fluorene epoxy acrylate may be prepared by reacting4,4-(9-fluorenylidene)-diphenol and epichlorohydrine to obtain an epoxycompound having a fluorene moiety, and the epoxy compound is reactedwith an acrylic acid to obtain a fluorenyl epoxy acrylate, which is thenfurther reacted with biphenyldianhydride and/or phthalic anhydride. Thereaction scheme may be summarized as below:

The multiple aromatic ring-containing polymer may include a functionalgroup represented by Chemical Formula D at one or both terminal ends:

-   -   wherein, in Chemical Formula D, Z³ is a moiety represented by        one of Chemical Formulae D-1 to D-7:

-   -   wherein, R^(b) and R^(c) are independently hydrogen, a        substituted or unsubstituted C1 to C20 alkyl group, an ester        group, or an ether group.

-   -   wherein, R^(d) is O, S, NH, a substituted or unsubstituted C1 to        C20 alkylene group, a C1 to C20 alkylamine group or a C2 to C20        alkenylamine group.

The multiple aromatic ring-containing polymer may be synthesized by aknown method or is commercially available (e.g., from Nippon SteelChemical Co., Ltd.).

The multiple aromatic ring-containing polymer may include a reactionproduct of a fluorene compound including9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-aminophenyl)fluorene,9,9-bis[4-(glyidyloxy)phenyl]fluorene, and9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene with an appropriate compoundcapable of reacting with the fluorene compound (e.g., an aromaticdianhydride including 9,9-bis-(3,4-dicarboxyphenyl)fluorene dianhydride,pyromellitic dianhydride (“PDMA”), biphenyltetracarboxylic dianhydride(“BPDA”), benzophenone tetracarboxylic dianhydride, andnaphthalenetetracarboxylic dianhydride, a C2 to C30 diol compound,epichlorohydrine, or the like).

The fluorene compound, dianhydrides, a diol compound, and the like arecommercially available, and the reaction conditions therebetween areknown in the art.

An acid value of the carboxylic acid polymer may be greater than orequal to about 50 mg KOH/g. For example, the acid value of thecarboxylic acid polymer may be greater than or equal to about 60 mgKOH/g, greater than or equal to about 70 mg KOH/g, greater than or equalto about 80 mg KOH/g, greater than or equal to about 90 mg KOH/g,greater than or equal to about 100 mg KOH/g, or greater than or equal toabout 110 mg KOH/g. The acid value of the polymer may be for exampleless than or equal to about 200 mg KOH/g, for example, less than orequal to about 190 mg KOH/g, less than or equal to about 180 mg KOH/g,or less than or equal to about 160 mg KOH/g.

The quantum dot (hereinafter, referred to as a semiconductornanocrystal) disposed (e.g., dispersed) in the polymer matrix is notparticularly limited. The quantum dot may be synthesized by a knownmethod or commercially available.

The quantum dot may include a Group III-VI compound, a Group III-Vcompound, a Group IV-VI compound, a Group IV element or compound, aGroup 1-III-VI compound, a Group I-II-IV-VI compound, or a combinationthereof. The quantum dot may not include cadmium.

The Group II-VI compound may include a binary element compound includingCdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, or amixture thereof; a temary element compound including CdSeS, CdSeTe,CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe,CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, ora mixture thereof; and a quaternary element compound including HgZnTeS,CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS,HgZnSeTe, HgZnSTe, or a mixture thereof. The Group II-VI compound mayfurther include Group III metal.

The Group IIII-V compound may include a binary element compoundincluding GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs,InSb, or a mixture thereof; a ternary element compound including GaNP,GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP,InNAs, InNSb, InPAs, InPSb, or a mixture thereof; and a quaternaryelement compound including GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb,GaInNP, GaInNAs, GaInNSb, GaInPAs, GalnPSb, InAlNP, InAlNAs, InAlNSb,InAlPAs, InAlPSb, or a mixture thereof. The Group IIII-V compound mayfurther include a Group II metal (e.g., InZnP)

The Group IV-VI compound may include a binary element compound includingSnS, SnSe, SnTe, PbS, PbSe, PbTe, or a mixture thereof; a ternaryelement compound including SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe,SnPbS, SnPbSe, SnPbTe, or a mixture thereof; and a quaternary elementcompound including SnPbSSe, SnPbSeTe, SnPbSTe, or a mixture thereof.

Examples of the Group 1-III-VI compound may include CuInSe₂, CuInS₂,CuInGaSe, and CuInGaS, but are not limited thereto. Examples of theGroup I-II-IV-VI compound may include CuZnSnSe and CuZnSnS, but are notlimited thereto.

The Group IV element or compound may include a single-element compoundincluding Si, Ge, or a mixture thereof; and a binary element compoundincluding SiC, SiGe, or a mixture thereof.

The binary element compound, the ternary element compound or thequaternary element compound respectively exist in a uniformconcentration in the particle or partially different concentrations inthe same particle. The semiconductor nanocrystal particle may have acore-shell structure wherein a first semiconductor nanocrystal may besurrounded by a second semiconductor nanocrystal that may be differentfrom the first semiconductor nanocrystal. The interface between the coreand the shell may have a concentration gradient wherein theconcentration of an element of the shell may change in a radialdirection.

The semiconductor nanocrystal may include a core and a multi-layeredshell surrounding the same. The multi-layered shell refers a shellincluding two or more layers. The adjacent layers may have the differentcomposition from each other. At least one layer of the multi-layeredshell may have a single composition, an alloying composition, or agradient alloy composition.

In a core-shell quantum dot, a compound of the shell may have a greaterenergy bandgap than a compound of the core. In the core-shell quantumdot, a compound of the shell may have a smaller energy bandgap than acompound of the core. In the multi-layered shell, an outer shell of acore may have a greater energy bandgap than a shell near to a core, butis not limited thereto.

The semiconductor nanocrystal may have quantum efficiency of greaterthan or equal to about 10%, for example, greater than or equal to about30%, greater than or equal to about 50%, greater than or equal to about60%, greater than or equal to about 70%, greater than or equal to about90%, or about 100%. For use in display devices, the semiconductornanocrystal may have a narrower spectrum so as to realize enhanced colorpurity or color reproducibility. The semiconductor nanocrystal may havea full width at half maximum (“FWHM”) of a light emitting wavelengthspectrum of less than or equal to about 45 nm, for example less than orequal to about 40 nm, or less than or equal to about 30 nm. Within suchranges, a device including the semiconductor nanocrystal may haveenhanced color purity or improved color reproducibility.

The quantum dot may have a particle size (the particle diameter for aspherical particle, and in case of a non-spherical particle, a diametercalculated from an area of a two dimensional TEM image) of about 1 nm toabout 100 nm. For example, the quantum dot may have a particle size ofabout 1 nm to about 20 nm. The quantum dot may have a particle size ofgreater than or equal to about 2 nm, or greater than or equal to about 3nm and less than or equal to about 15 nm, less than or equal to about 14nm, less than or equal to about 13 nm, less than or equal to about 12nm, less than or equal to about 10 nm, or less than or equal to about 9nm.

A shape of the quantum dot is not particularly limited. In anembodiment, the quantum dot may have a spherical shape, an ellipsoidalshape, a pyramidal shape, multi-armed (multi-pod) shape, cubic shape, apolygonal shape, a nanorod, a nanotube, a nanowire, a nanofiber, ananosheet, or a combination thereof.

The quantum dot is commercially available or may be synthesized in anymethod. For example, quantum dots may be a colloidal particlesynthesized according to a wet chemical process. In the wet chemicalprocess, precursors react in an organic solvent to grow nanocrystalparticles, and the organic solvent or a ligand compound may coordinateto the surface of the quantum dot, controlling the growth of thenanocrystal. Examples of the organic solvent and the ligand compound areknown. In the wet chemical process, the synthesized colloidal quantumdot may be collected by adding a non-solvent to a reaction solution andcentrifuging a final mixture. Such a collecting process may causeremoval of at least a portion of the organic materials coordinated onthe surface of the quantum dot. Examples of the non-solvent may beacetone, ethanol, methanol, and the like, but are not limited thereto.

The quantum dot may have an organic ligand bound to its surface. In anembodiment, the organic ligand may have a hydrophobic moiety. Theorganic ligand may be RCOOH, RNH₂, R₂NH, RAN, RSH, R₃PO, R₃P, ROH,RCOOR′, RPO(OH)₂, R₂POOH (wherein, R and R′ are independently a C5 toC24 substituted or unsubstituted aliphatic hydrocarbon group, forexample a C5 to C24 alkyl group, a C5 to C24 alkenyl group, or a C5 toC20 aromatic hydrocarbon group, for example a C6 to C20 aryl group), ora combination thereof.

Examples of the organic ligand may include thiol compounds such asmethane thiol, ethane thiol, propane thiol, butane thiol, pentane thiol,hexane thiol, octane thiol, dodecane thiol, hexadecane thiol, octadecanethiol, or benzyl thiol; amines such as methane amine, ethane amine,propane amine, butane amine, pentyl amine, hexyl amine, octyl amine,nonylamine, decylamine, dodecyl amine, hexadecyl amine, octadecyl amine,dimethyl amine, diethyl amine, dipropyl amine, tributylamine, ortrioctylamine; carboxylic acid compounds such as methanoic acid,ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoicacid, heptanoic add, octanoic acid, dodecanoic add, hexadecanoic acid,octadecanoic add, oleic acid, or benzoic acid; an alkyl phosphinecompound such as methyl phosphine, ethyl phosphine, propyl phosphine,butyl phosphine, pentyl phosphine, octylphosphine, dioctyl phosphine,tributylphosphine, or trioctylphosphine; a phosphine oxide compound suchas methyl phosphine oxide, ethyl phosphine oxide, propyl phosphineoxide, butyl phosphine oxide, pentyl phosphine oxide, tributyl phosphineoxide, octylphosphine oxide, dioctyl phosphine oxide, or trioctylphosphine oxide; diphenyl phosphine, triphenyl phosphine, or oxidecompounds thereof; a C5 to C20 alkyl phosphonic acid; a C5 to C20 alkylphosphinic acid such as hexylphosphinic acid, octylphosphinic acid,dodecylphosphinic acid, tetradeceylphosphinic acid, hexadecylphosphinicacid, or octadecylphosphinic acid; and the like, but are not limitedthereto. The quantum dot may include the organic ligand alone or as amixture of two or more.

The photoluminescent layer including the quantum dot-polymer compositepattern may have potential utility in a color filter of a liquid crystaldisplay. A conventional liquid crystal display device includes abacklight unit, a liquid crystal layer, and an absorption-type colorfilter. When white light emitted from a backlight unit passes anabsorption-type color filter, light in a predetermined wavelength maytransmit and the rest of light may be absorbed, and thereby apredetermined color in each pixel may be realized. In such a liquidcrystal display device, the absorption-type color filter may causesubstantial luminous efficiency deterioration.

The quantum dot may have a theoretical quantum yield (“QY”) of about100%, and may emit light having high color purity (e.g., a full width athalf maximum (“FWHM”) of less than or equal to about 40 nm). When thephotoluminescent layer having the quantum dot-polymer composite is usedas a color filter, a display device having a wider viewing angle andmore enhanced brightness may be realized. The color filter having thephotoluminescent layer may increase luminous efficiency of a device andimprove color reproducibility of a device in comparison with a colorfilter including light absorption-type material.

However, light emitting properties of the quantum dot may be adverselyaffected by heat and/or an external environment (e.g., matrix, oxygen,moisture, and the like) compared with an absorption-type color filtermaterial. In order to realize a display device having enhancedbrightness, a quantum dot-polymer matrix pattern may be required tomaintain a high photoconversion efficiency, but a final quantumdot-polymer composite pattern obtained through each and every process(of preparation of a composition for forming a light-based pattern,subsequently heat-treatment, and the like) may show a significantlydecreased photoconversion efficiency and/or a maintenance ratio of theremarkably-deteriorated photoconversion efficiency. Cadmium-free quantumdots (e.g., quantum dots including a Group IIII-V core such as InP) areknown to have greatly inferior thermal/chemical stability tocadmium-based quantum dots and thus may show sharply decreased lightconversion efficiency even with a heat-treating at a relatively lowtemperature, which may lead to decreased brightness in the displaydevice.

However, in order to form the quantum dot-polymer composite pattern byusing an alkali developing solution, the heat treatment carried out at arelatively high temperature, for example, greater than or equal to 160°C. (e.g., greater than or equal to 180° C. and even about 230° C.) maybe inevitable and unavoidable. Accordingly, using a color filter withthe quantum dot-polymer composite pattern has been very limited so far.

In a layered structure according to an embodiment, a capping layerincluding an inorganic material (e.g., essentially consisting of orconsisting of an inorganic material) may be provided (for example,directly) on the photoluminescent layer (e.g., on the quantum dotpolymer composite pattern or on a surface of each section in thepattern), and the foregoing structure may contribute toreduction/prevention of a decrease in the light emitting properties ofthe quantum dot.

The capping layer may be disposed directly on the photoluminescentlayer. In an embodiment, at least a portion of an exposed surface of therepeating section (e.g., first section, second section and/or thirdsection) of the quantum dot-polymer composite pattern may be coated withthe inorganic material. (See: FIGS. 1 and 2 )

The inorganic material may have a refractive index of about 1.4 to about3.0.

The inorganic material may include a silicon oxide, a silicon nitride, asilicon oxynitride, a hafnium oxide, a tantalum oxide, a titanium oxidesuch as titanium dioxide, a zirconium oxide, a zinc oxide, a zincsulfide, a magnesium oxide, a cesium oxide, a lanthanum oxide, an indiumoxide, a niobium oxide, an aluminum oxide, or a combination thereof. Thecapping layer may include a continuous film of the inorganic material.

The capping layer may include at least two (e.g., three, four, five,six, seven, or more) layers including the inorganic material. Theadjacent layers 1 and 2 may be different in a composition of theinorganic material, refractive index, transmittance, a thickness, orcombination thereof of the inorganic material. (See: FIG. 3 )

Lamination of the capping layer with the photoluminescent layers and/orthe transparent substrate may cause a stress. In the adjacent layers,controlling a composition of the inorganic material, a refractive index,a thickness, or combination thereof of each layer may allow to control(e.g., minimize) the stress. In addition, the capping layer may play arole of a dichroic filter or a dichroic reflector by adjusting acomposition of the inorganic material, a refractive index, orcombination thereof of each layer in the adjacent layers. By adjusting acomposition, a refractive index, transmittance, a thickness, and thelike of each layer, a total light transmittance (e.g., regarding excitedlight) may be maintained at a level of greater than or equal to about90%, for example, greater than or equal to about 95%, or even greaterthan or equal to about 99% while the transmission of oxygen and moisturemay be suppressed. The quantum dot included in the photoluminescentlayer may emit light in all directions. When the capping layer of thelayered structure plays a role of a dichroic filter and/or reflector,light of a predetermined wavelength emitted by the photoluminescentlayer (e.g., green light or red light) may be mostly reflected in apredetermined direction (e.g., a front direction of a liquid crystaldisplay device that will be described later), which may bring forth anincrease in terms of light utilization efficiency.

In an embodiment, the capping layer may include a first layer includinga first inorganic material and a second layer including a secondinorganic material, directly contacting the first layer, and having adifferent refractive index from the first layer by at least about 0.5.The capping layer may include the first layer and the second layerdisposed alternately.

The first inorganic material may have a composition different from thatof the second inorganic material. The first inorganic material may havea lower refractive index than the second inorganic material. In anembodiment, the capping layer may include a plurality of layers having adifferent refractive index with each other. For example, two layershaving a different refractive index with each other (e.g., a layerincluding a material having a high refractive index and a layerincluding a material having a relatively low refractive index) may bealternately laminated.

The first inorganic material may include a silicon oxide. The secondinorganic material may include a hafnium oxide, a tantalum oxide, atitanium oxide, a zirconium oxide, a magnesium oxide, a cesium oxide, alanthanum oxide, an indium oxide, a niobium oxide, an aluminum oxide, asilicon nitride, or a combination thereof.

In the multi-layered capping layer, a thickness of each layer and thenumber of layers may be determined considering a refractive index or areflection wavelength of each layer, and a thickness of the first layermay be from about 3 nm to about 300 nm and a thickness of the secondlayer may be from about 3 nm to about 300 nm. The thickness of the firstlayer may be greater than the thickness of the second layer. Thethickness of the first layer may be smaller than the thickness of thesecond layer.

A total thickness of the capping layer may be greater than or equal toabout 100 nm, for example, greater than or equal to about 200 nm, orgreater than or equal to about 300 nm. A total thickness of the cappinglayer may be less than or equal to about 10000 nm, less than or equal toabout 8000 nm, less than or equal to about 6000 nm, less than or equalto about 5000 nm, less than or equal to about 400 nm, or less than orequal to about 3000 nm.

The capping layer may have a transmittance of greater than or equal toabout 90%, for example, greater than or equal to about 95%, greater thanor equal to about 96%, greater than or equal to about 97%, greater thanor equal to about 98%, or greater than or equal to about 99% for lighthaving a wavelength of greater than or equal to about 380 nm and lessthan or equal to about 520 nm (e.g., less than or equal to about 510 nm,less than or equal to about 500 nm, less than or equal to about 490 nm,or less than or equal to about 480 nm).

A layered structure according to an embodiment may include for examplean overcoat layer on the capping layer so as to realize planarization.The overcoat layer may include an organic polymer. The organic polymermay include any optically transparent polymer, but is not particularlylimited. For example, the organic polymer may be a thermosetting resinand an ultraviolet (“UV”) curable resin. The thermosetting resin andultraviolet (“UV”) curable resin for the overcoat layer (“OCL”) mayinclude a urethane (meth)acrylate resin, a perfluoropolymer having a(meth)acrylate group, poly(meth)acrylate having a (meth)acrylate group,an epoxy(meth) acrylate polymer, or a combination thereof. A thicknessof the overcoat layer is not particularly limited and may beappropriately selected. For example, the thickness of the overcoat layermay be different in accordance with a thickness or planarity of a colorfilter, and may be less than or equal to about 5 μm, for example, lessthan or equal to about 4 μm, or less than or equal to about 3 μm, but isnot limited thereto. The thickness of the overcoat layer may be greaterthan or equal to about 10 nm, greater than or equal to about 50 nm,greater than or equal to about 80 nm, or greater than or equal to about100 nm but is not limited thereto.

According to an embodiment, the layered structure may show an improvedlight conversion maintenance ratio after a heat treatment at anincreased temperature (e.g., greater than or equal to about 160° C.,even greater than or equal to about 180° C., or greater than or equal toabout 200° C.). In addition, the layered structure according to anembodiment may show not a deteriorated but maintained or even increasedlight conversion maintenance ratio when excited by light under a severeenvironment (e.g., a temperature of about 65° C. and relative humidityof about 85%) after the heat treatment.

In an embodiment, a method of producing the layered structure includes

-   -   applying a composition (hereinafter, also referred to as a        photosensitive composition) including a plurality of quantum        dots, a photopolymerizable compound including at least two        polymerizable moieties, a linear polymer having a carboxylic        acid group-containing repeating unit (e.g., a binder), a        photoinitiator, and an organic solvent (for example, on a        transparent substrate) to form a film;    -   exposing a predetermined region of the formed film to light (for        example having a wavelength of less than 410 nm) to perform a        cross-linking polymerization in an exposed region and to form a        quantum dot polymer composite including the plurality of quantum        dots dispersed in a polymer matrix;    -   removing an unexposed region from the film using an alkali        aqueous solution to obtain a quantum dot-polymer composite        pattern;    -   forming a capping layer including an inorganic material on the        quantum dot-polymer composite pattern (for example, after        removing the unexposed region); and    -   heating the quantum dot-polymer composite pattern at a        temperature of greater than or equal to about 160° C. after        forming the capping layer including the inorganic material.

In the method, the series of the processes may be repeated at leasttwice so that the quantum dot polymer composite pattern of thephotoluminescent layer may have a plurality of sections (e.g., a firstsection, a second section, or optionally a third section).

The quantum dot, the photopolymerizable compound, the carboxylic acidpolymer (binder), the transparent substrate, the polymer matrix, thequantum dot-polymer composite, and the capping layer may be the same asexplained above.

The composition includes a photoinitiator. Types of the photoinitiatorare not particularly limited, and may be selected appropriately. Forexample, the available photoinitiator may include a triazine-basedcompound, an acetophenone-based compound, a benzophenone-based compound,a thioxanthone-based compound, a benzoin-based compound, an oxime-basedcompound, or a combination thereof, but it is not limited thereto.

Examples of the triazine-based compound may include2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(3′,4′-dimethoxy styryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4′-methoxy naphthyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxy phenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis(trichloro methyl)-s-triazine,2-biphenyl-4,6-bis(trichloro methyl)-s-triazine, 2,4-bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphthol-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxy naphthol-yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis(trichloro methyl)-6-(piperonyl)-s-triazine,or 2,4-bis(trichloro methyl)-6-(4′-methoxy styryl)-s-triazine but it isnot limited thereto.

Examples of the acetophenone-based compound may be 2,2′-diethoxyacetophenone, 2,2′-dibutoxy acetophenone, 2-hydroxy-2-methylpropinophenone, p-t-butyl trichloro acetophenone, p-t-butyl dichloroacetophenone, 4-chloro acetophenone, 2,2′-dichloro-4-phenoxyacetophenone, 2-methyl-1-(4-(methylthio)phenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethyl amino-1-(4-morpholinophenyl)-butan-1-one, but are not limited thereto.

Examples of the benzophenone-based compound may be benzophenone, benzoylbenzoate, benzoyl methyl benzoate, 4-phenyl benzophenone, hydroxybenzophenone, acrylated benzophenone, 4,4′-bis(dimethylamino)benzophenone, 4,4′-dichloro benzophenone, 3,3′-dimethyl-2-methoxybenzophenone, but are not limited thereto.

Examples of the thioxanthone-based compound may be thioxanthone,2-methyl thioxanthone, 2-isopropyl thioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropyl thioxanthone, 2-chloro thioxanthone, andthe like, but are not limited thereto.

Examples of the benzoin-based compound may include benzoin, benzoinmethyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoinisobutyl ether, or benzyl dimethyl ketal, but are not limited thereto.

Examples of the oxime-based compound may include2-(o-benzoyloxime)-1-[4-(phenylthio)phenyl]-1,2-octandione and1-(o-acetyloxime)-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone,but are not limited thereto.

The photoinitiator may also be a carbazole-based compound, a diketonecompound, a sulfonium borate-based compound, a diazo-based compound, abiimidazole-based compound, and the like, in addition to thephotoinitiator.

The composition may include a solvent. The solvent may be appropriatelyselected considering affinity for other components in the composition(e.g., a carboxylic acid polymer, a photopolymerizable compound, aphotoinitiator, other additives, and the like), affinity for an alkalideveloping solution, a boiling point, and the like. The composition mayinclude the solvent in a balance amount except for the amounts ofdesired solids (non-volatile powder).

Non-limiting examples of the solvent may include ethylene glycols suchas ethylene glycol, diethylene glycol, or polyethylene glycol;glycolethers such as ethylene glycolmonomethylether, ethyleneglycolmonoethylether, diethylene glycolmonomethylether, ethyleneglycoldiethylether, or diethylene glycoldimethylether; glycol etheracetates such as ethylene glycol monomethyl ether acetate, ethyleneglycolmonoethyletheracetate, diethylene glycolmonoethyletheracetate, ordiethylene glycolmonobutyletheracetate; propylene glycols such aspropylene glycol; propylene glycolethers such as propyleneglycolmonomethylether, propylene glycolmonoethylether, propyleneglycolmonopropylether, propylene glycolmonobutylether, propyleneglycoldimethylether, dipropylene glycoldimethylether, propyleneglycoldiethylether, or dipropylene glycoldiethylether; propyleneglycoletheracetates such as propylene glycolmonomethyl ether acetate, ordipropylene glycolmonoethyletheracetate; amides such asN-methylpyrrolidone, dimethyl formamide, dimethyl acetamide; ketonessuch as methylethylketone (“MEK”), methylisobutylketone (“MIBK”), orcyclohexanone; petroleums such as toluene, xylene, or solvent naphtha;esters such as ethyl 3-ethoxy propionate, ethyl acetate, butyl acetate,or ethyl lactate; ethers such as diethyl ether, dipropyl ether, dibutylether, or a mixture thereof.

If desired, the photosensitive composition may further include variousadditives such as a light diffusing agent, a leveling agent, or acoupling agent in addition to the aforementioned components. The amountof the additive is not particularly limited, and may be controlledwithin an appropriate range wherein the additive does not cause anadverse effect on the photosensitive composition and the patternobtained therefrom.

The light diffusing agent may increase a refractive index of thecomposition in order to increase a chance of the incident light to meetwith quantum dots. The light diffusing agent may include inorganic oxideparticles such as alumina, silica, zirconia, titanium oxide, or zincoxide particulates, and metal particles such as gold, silver, copper, orplatinum, but is not limited thereto. A particle size of the lightdiffusing agent may be greater than or equal to about 30 nm, forexample, greater than or equal to about 50 nm and less than or equal toabout 1000 nm, for example, less than or equal to about 500 nm, lessthan or equal to about 400 nm, or less than or equal to about 300 nm,but is not limited thereto.

The leveling agent may prevent stains or spots and improve planarizationand leveling characteristics of a film, and examples thereof may includethe following but are not limited thereto.

A fluorine-based leveling agent may include commercial products, forexample BM-1000™ and BM-1100™ of BM Chemie Inc.; MEGAFACE F 142D™, F172™, F 173™, and F 183™ of Dainippon Ink Kagaku Kogyo Co., Ltd.;FC-135™, FC-170C™, FC-430™, and FC-431™ of Sumitomo 3M Co., Ltd.;SURFLON S-112™, SURFLON S-113™, SURFLON S-131™, SURFLON S-141™, andSURFLON S-145™ of Asahi Glass Co., Ltd.; and SH-28PA™, SH-190™, SH-193™,SZ-6032™, SF-8428™, and the like of Toray Silicone Co., Ltd.

The coupling agent may increase adherence with respect to the substrateand examples thereof may include a silane-based coupling agent Examplesof the silane-based coupling agent may be vinyl trimethoxysilane, vinyltris(2-methoxyethoxysilane), 3-glycidoxypropyl trimethoxysilane,2-(3,4-epoxy cyclohexyl)ethyl trimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyl trimethoxysilane,3-methacryloxylpropyl trimethoxysilane, 3-mercaptopropyltrimethoxysilane, and the like.

Amounts of each component in the composition are not particularlylimited and may be adjusted as necessary. For example, the compositionmay include

-   -   about 1 weight % (wt %) to about 40 wt % of the quantum dot;    -   about 0.5 wt % to about 35 wt % of the carboxylic acid polymer;    -   about 0.5 wt % to about 30 wt % of the photopolymerizable        compound;    -   optionally about 0.1 wt % to about 40 wt % of the thiol        compound; and    -   about 0.01 wt % to about 10 wt % of the photoinitiator; and    -   a balance amount of the solvent    -   based on a total weight of the composition, but is not limited        thereto.

A content of the quantum dot including the organic ligand may be greaterthan or equal to about 1 wt %, for example, greater than or equal toabout 5 wt %, or greater than or equal to about 10 wt % based on a totalweight of the composition. A content of the quantum dot including theorganic ligand may be less than or equal to about 40 wt %, for example,less than or equal to about 35 wt % based on a total weight of thecomposition. In an embodiment, a content of the quantum dot includingthe organic ligand may be about 1.5 wt % to about 60 wt % based on atotal weight of solid contents (i.e., non-volatile components forexample, the quantum dot polymer composite) of the composition.

The composition may further include the additive, and kinds and contentsthereof may be controlled within an appropriate range wherein theadditive does not cause an adverse effect on the composition and thepattern, are not particularly limited.

In the composition, a plurality of quantum dots are dispersed (e.g.,separated from one another) by the carboxylic acid polymer to formquantum dot dispersion. Accordingly, the composition may include quantumdot dispersion and the quantum dot dispersion may include a plurality ofquantum dots dispersed in the carboxylic acid polymer and the carboxylicacid polymer. The quantum dot dispersion may further include a solvent.

A method of producing the composition includes preparing a bindersolution including the carboxylic acid polymer and the solvent;dispersing the plurality of quantum dots in the binder solution toobtain quantum dot-binder dispersion; and mixing the quantum dot-binderdispersion with at least one of the thiol compound; the photoinitiator;the photopolymerizable monomer and the solvent. A mixing manner is notparticularly limited, and may be appropriately selected. For example,each component may be mixed sequentially or simultaneously.

The method of producing the composition may further include selectingquantum dots including an organic ligand (e.g., having a hydrophobicmoiety) on the surface, and selecting a carboxylic acid polymer capableof dispersing the quantum dots. In the selecting the carboxylic acidpolymer, a chemical structure and an acid value of a correspondingpolymer may be considered. In order to disperse quantum dots, thecarboxylic acid polymer may have an acid value of greater than or equalto about 50 mg KOH/g which may be different depending on a chemicalstructure (e.g., chemical structures of a binder backbone or ahydrophobic moiety at a side chain) of the polymer For example, thecarboxylic acid polymer may have an acid value of greater than or equalto about 60 mg KOH/g, greater than or equal to about 70 mg KOH/g,greater than or equal to about 80 mg KOH/g, greater than or equal toabout 90 mg KOH/g, greater than or equal to about 100 mg KOH/g, orgreater than or equal to about 110 mg KOH/g. The carboxylic acid polymermay have for example an acid value of less than or equal to about 250 mgKOH/g, less than or equal to about 230 mg KOH/g, less than or equal toabout 200 mg KOH/g, less than or equal to about 190 mg KOH/g, less thanor equal to about 180 mg KOH/g, or less than or equal to about 160 mgKOH/g, but is not limited thereto. The quantum dots may be mixed in asolution including the binder having an acid value within the ranges toform quantum dot-binder dispersion, the formed quantum dot-binderdispersion may exhibit improved compatibility with other components inthe composition for forming the photoluminescent layer (e.g.,photopolymerizable compound, photoinitiator, solvent, etc.) and thus thequantum dots may be dispersed so that they may form a pattern in thefinal composition (i.e., the composition for forming thephotoluminescent layer).

The composition may be coated on a transparent substrate by anappropriate manner (e.g., spin coating) to form a film. The formed filmmay be subjected to pre-baking as needed. The pre-baking may beperformed at a temperature of less than or equal to about 130° C., forexample, about 90° C. to about 120° C. A time of the pre-baking is notparticularly limited and may be appropriately selected. For example, thepre-baking may be performed for greater than or equal to about 1 minuteand less than or equal to about 60 minutes, but is not limited thereto.The pre-baking may be performed under a predetermined atmosphere (e.g.,air, oxygen-free atmosphere, inert gas atmosphere), is not particularlylimited thereto.

In the exposed region, cross-linking polymerization may occur to form aquantum dot polymer composite having the plurality of the quantum dotsdispersed in the polymer matrix. The resulting film may be treated withan alkali aqueous solution to remove the unexposed region from the filmand to obtain a pattern of the quantum dot polymer composite. Thephotosensitive composition may be developable by an alkali aqueoussolution, and when the photosensitive composition is used, a pattern ofthe quantum dot-polymer composite may be formed without using an organicsolvent developing solution.

A non-limiting method of forming a pattern is explained referring toFIG. 4 . The composition may be coated on a predetermined substrate(e.g., a glass substrate or a glass substrate coated with apredetermined thickness of SiNx (protective layer) (e.g., about 500 Å toabout 1500 Å of the protective layer)) in an appropriate manner such asspin coating or slit coating to form a film of a predetermined thickness(e.g., a thickness of about 3 μm to about 30 μm). The formed film may bepre-baked, if desired. The formed (or optionally pre-baked) film may beexposed to light having a predetermined wavelength under a mask having apredetermined pattern. A wavelength and intensity of the light may beselected considering kinds and contents of the photoinitiator, kinds andcontents of the quantum dots, and the like.

The exposed film may be treated (e.g., dipped or sprayed) with an alkalideveloping solution and thus an unexposed part of the film may dissolveto form the quantum dot polymer composite pattern.

After removing the unexposed region, a capping layer including aninorganic material may be formed on the predetermined region as exposedto light (e.g., on the quantum dot polymer composite pattern). Beforeforming the capping layer, the predetermined region as exposed to light(e.g., the patterned region) may be heat-treated at a temperature ofgreater than or equal to (the organic solvent's boiling point—10° C.)(e.g., greater than or equal to about a boiling point of the organicsolvent) and less than about 160° C. (e.g., when the organic solvent ispropylene glycol methyl ether acetate (“PGMEA”), the temperature may bein a range of about 145° C. to about 152° C.) (hereinafter, alsoreferred as “an inter POB” process).

Details of the inorganic material and the capping layer may be the sameas set forth above. A formation of the capping layer may be performed byphysical vapor deposition, chemical vapor deposition, or a combinationthereof. Specific conditions for the forming process of the cappinglayer may be different depending on kinds of the inorganic material.

The physical vapor deposition may be performed by a thermal vacuummethod, a sputtering method, and/or an electron beam method. Thephysical vapor deposition may be performed by a commercially availableapparatus and a known method considering kinds of an inorganic materialand a structure/thickness of the capping layer. An atmosphere, atemperature, a target material, and a vacuum degree of the depositionmay be appropriately selected and is not particularly limited. A mannerof the chemical vapor deposition is not particularly limited and may beappropriately selected. The chemical vapor deposition may be performedby manners of normal pressure CVD, low pressure CVD, ultra high vacuumCVD, plasma CVD, and the like, but is not limited thereto. The chemicalvapor deposition may be performed by a commercially available apparatusand a known method considering kinds of an inorganic material and astructure/thickness of the capping layer. An atmosphere, a temperature,kinds of gases, and a vacuum degree of the deposition may beappropriately selected and is not particularly limited.

The capping layer may be formed on the formed quantum dot polymercomposite pattern mainly in order to protect and shield the quantum dotfrom moisture. In some embodiments, the formation of the capping layerincludes deposition with using a thin film process equipment. When aphysical vapor deposition (hereinafter, referred to as PVD) equipment isused, the capping layer may be formed at room temperature. In someembodiments, alternating deposition of different materials may beconducted in order to realize smaller reflectance and minimize theoccurrence of defects. During the alternating deposition, the thicknessof each layer may be dependent on an optical design value, and theoptimized thickness may be determined considering the minimization ofthe reflectance. The optical design value indicates, for example, acombination of optical thicknesses. The thickness for the minimizedreflectance may be obtained through an optical simulation by using acommercially available program, for example, Essential Macleod and thelike.

In case of the multilayered capping layer, a total number of the layersmay be greater than or equal to about two (2) and less than or equal toabout 10. In the case of using a chemical vapor deposition (“CCVD”)equipment, the deposition may be performed at a temperature of about120° C. to about 180° C. The deposition manner, e.g., conditions, may besubstantially the same as or similar to those for the PVD.

The method may include heat-treating the layered structure at greaterthan or equal to about 160° C. and less than or equal to about 250° C.or for example less than or equal to about 240° C. (e.g., a temperatureof about 160° C. to about 230° C.) (hereinafter, referred to as apost-baking process or a POB process) after the deposition (or theformation) of the capping layer. The post-baking process may improveresistance against crack and against a solvent of the quantum dotpolymer composite pattern. Duration for the post-baking may be selectedappropriately without particular limitation. For example, thepost-baking process may be carried out for a time greater than or equalto about 5 minutes, for example, greater than or equal to about 10minutes or greater than or equal to about 20 minutes but is not limitedthereto. For example, the post-baking process may be performed for lessthan or equal to about 60 minutes, for example, less than or equal toabout 40 minutes or less than or equal to about 35 minutes but is notlimited thereto.

In some embodiments, the layered structure may exhibit improvedstability such that it may maintain its photoconversion efficiency at alevel of greater than or equal to about 90% of the initialphotoconversion efficiency, even after the post-baking process.Accordingly, the layered structure of some embodiments may either showsubstantially no decrease in the photoconversion efficiency or exhibitan increased photoconversion efficiency under a predeterminedenvironment (e.g., when it is irradiated with excitation light at atemperature of about 65° C. and under a relative humidity of about 85%).

When the layered structure is used as a color filter, two or three typesof photosensitive compositions including red light emitting quantumdots, green light emitting quantum dots, (or optionally, blue lightemitting quantum dots) may be prepared, and the patterning process maybe repeated necessary times (e.g., at least twice or three times) foreach composition.

In an embodiment, an electronic device includes the layered structure.The electronic device may be a photoluminescent liquid crystal display.The liquid crystal display may include a liquid crystal panel includinga lower substrate, an upper substrate, a liquid crystal layer disposedbetween the upper and lower substrates, and a photoluminescent colorfilter layer provided on the upper substrate; a polarizer disposed underthe lower substrate; and a backlight unit disposed under the polarizerand emitting blue light, wherein the photoluminescent color filter layerincludes the layered structure.

FIG. 5 is a cross-sectional view showing a liquid crystal displayaccording to an embodiment. Referring to FIG. 5 , a photoluminescentliquid crystal display device comprises a liquid crystal panel 200, alower polarizer 300 disposed under the liquid crystal panel 200, and abacklight unit (“BLU”) disposed under the lower polarizer 300. Thebacklight unit includes (e.g., blue) light source 110. The backlightunit may further include a light guide panel 120. The backlight unit maynot include a light guide panel.

The liquid crystal panel 200 includes a lower substrate 210, an uppersubstrate 240, a liquid crystal layer 220 disposed between the upper andlower substrates, and a photoluminescent color filter layer provided onthe upper substrate. The photoluminescent color filter layer includes aphotoluminescent layer including a pattern of a quantum dot polymercomposite; and a capping layer disposed on the photoluminescent layerand including an inorganic material.

The lower substrate 210, also referred to as an array substrate, may bea transparent insulation material substrate (e.g., a glass substrate, apolymer substrate including a polyester such as polyethyleneterephthalate (“PET”) or polyethylene naphthalate (“PEN”),polycarbonate, and/or a polyacrylate, inorganic material substrate of apolysiloxane, Al₂O₃, or ZnO. A wire plate 211 may be disposed on thelower substrate 210. The wire plate 211 may include a plurality of gatewires (not shown) and data wires (not shown) that define a pixel area, athin film transistor disposed adjacent to a crossing region of gatewires and data wires, and a pixel electrode for each pixel area, but isnot limited thereto. Details of such a wire plate are known and are notparticularly limited.

The liquid crystal layer 220 may be disposed on the wire plate 211. Theliquid crystal layer 220 may include an alignment layer 221 on and underthe liquid crystal layer 220 to initially align the liquid crystalmaterial included therein. Details (e.g., a liquid crystal material, analignment layer material, a method of forming liquid crystal layer, athickness of liquid crystal layer, or the like) of the liquid crystalmaterial and the alignment layer are known and are not particularlylimited.

A lower polarizer 300 may be provided under the lower substrate.Materials and structures of the lower polarizer 300 are known and arenot particularly limited. A backlight unit (e.g., emitting blue light)may be disposed under the lower polarizer 300. An upper optical elementsuch as an upper polarizer 300 may be disposed on the upper substrate,for example, provided between the liquid crystal layer 220 and the uppersubstrate 240, in particular, between the liquid crystal layer 220 andthe photoluminescence color filter, but is not limited thereto. Thepolarizer may be any polarizer that used in a liquid crystal displaydevice. The polarizer may be triacetyl cellulose (“TAC”) having athickness of less than or equal to about 200 μm, but is not limitedthereto. In an alternative embodiment, the upper optical element may bea coating that controls a refractive index without a polarizationfunction.

The backlight unit includes a light source emitting blue light. In anembodiment, the backlight unit may be an edge-type lighting. Forexample, the backlight unit may include a reflector (not shown), a lightguide (not shown) provided on the reflector and providing a planar lightsource with the liquid crystal panel 200, and/or at least one opticalsheet (not shown) on the light guide, for example, a diffusion plate, aprism sheet, and the like, but is not limited thereto.

In an embodiment, the backlight unit may be a direct lighting. Forexample, the backlight unit may have a reflector (not shown), and mayhave a plurality of fluorescent lamps disposed on the reflector atregular intervals, or may have a light-emitting diode (“LED”) operatingsubstrate on which a plurality of LEDs may be disposed, a diffusionplate thereon, and optionally at least one optical sheet.

Details (e.g., each components of light guide and various opticalsheets, a reflector, and the like) of such a backlight unit are knownand are not particularly limited.

The upper substrate 210 may be the transparent substrate. A black matrix241 may be provided under the upper substrate and may have an openingand hides the gate line, the data line, and the thin film transistor ofthe wire plate on the lower substrate. For example, the black matrix 241may have a lattice shape. In openings of the black matrix 241, aphotoluminescent layer 230 including a first section (R) configured toemit light (e.g., red light) in a first peak wavelength, a secondsection (G) configured to emit light (e.g., green light) in a secondpeak wavelength, and a third section (B) configured to emit or transmitfor example blue light may be provided. If desired, the photoluminescentcolor filter layer may further include at least one of a fourth section.The fourth section may include a quantum dot emitting a light ofdifferent colors (e.g., cyan, magenta, and yellow) from the lightemitted from the first to third sections.

In the photoluminescent layer 230, sections forming a pattern may berepeated corresponding to pixel areas formed on the lower substrate. Atransparent common electrode 231 may be provided on the photoluminescentcolor filter layer.

The third section (B) configured to emit or transmit blue light may be atransparent color filter that does not change a light emitting spectrumof the light source. In this case, blue light emitted from the backlightunit may pass the polarizer and the liquid crystal layer to become apolarized state, then enter the third section (B) in a polarized state,and may be go out of the third section (B) as it is. If needed, thethird section may include quantum dots emitting blue light.

If needed, the photoluminescent liquid crystal display device mayfurther have a blue light blocking layer (blue cut filter). The bluelight blocking layer (e.g., a blue cut filter) may be disposed betweenlower surfaces of the first section (R) and the second section (G) andthe upper substrate 240 or on the upper substrate (not shown). The bluelight blocking layer may include a sheet having an opening in a regioncorresponding to a pixel area (a third section) displaying blue and thusformed in a region corresponding to first and second sections. In anembodiment, the blue light blocking layer may be formed by alternatelystacking at least two layers having different refractive indexes andthus may block light in a blue wavelength region but transmit light inthe other wavelength regions. The blocked blue wavelength light may bereflected and recycled. The blue light blocking layer may play a role ofblocking light emitted from a blue light source 110 from being directlyemitted outside.

Hereinafter, the embodiments are illustrated in more detail withreference to examples. However, they are exemplary embodiments, and theembodiments are not limited thereto.

EXAMPLES

Measurement Method:

A photoconversion efficiency and a maintenance ratio are obtained in thefollowing method:

-   -   [1] A blue light photoconversion efficiency of a quantum dot        polymer composite film is obtained by the following procedures.        The prepared quantum dot polymer composite is inserted between a        light guide and an optical sheet of a 60 inch television (“TV”)        equipped with blue LED having a peak wavelength of 449 nm. The        TV is operated and light emitting properties are analyzed with a        spectroradiometer (CS-2000, Konica Minolta Co.) 45 cm away        therefrom and a spectrum of light emitted therefrom is obtained.        The light emitting spectrum is used to calculate the        photoconversion efficiency.    -   [2] A maintenance ratio is a ratio of a photoconversion        efficiency after the process relative to a photoconversion        efficiency before the process.

Reference Example 1: Preparation of (Green Light-Emitting or RedLight-Emitting) Non-Cadmium Quantum Dot

(1) 0.2 mmol of indium acetate, optionally 0.1 mmol of zinc oleate, 0.6mmol of palmitic acid, and 10 milliliters (mL) of 1-octadecene are putin a reactor and heated at 120° C. under vacuum. After 1 hour, anatmosphere in the reactor is replaced with nitrogen. The reactor isheated at 280° C., a mixed solution of tris(trimethylsilyl)phosphine(“TMS3P”, 0.1 mmol) and trioctylphosphine (0.5 mL) is rapidly injectedthereinto, and the mixture is reacted for 20 minutes. Subsequently,acetone is added to the reaction solution rapidly cooled down to roomtemperature, and a precipitate obtained by centrifuging the mixture isdispersed in toluene to obtain the InP or InZnP core nanocrystals.

0.3 mmol (0.056 g) of zinc acetate, 0.6 mmol (0.189 g) of oleic acid,and 10 mL of trioctylamine are put in a reaction flask andvacuum-treated at 120° C. for 10 minutes. The reaction flask is heatedup to 220° C. after substituting inside of the reaction flask with N₂.After the toluene dispersion of the InP semiconductor nanocrystal (OD:0.15) and 0.6 mmol of S/TOP (sulfur dissolved or dispersed in trioctylphosphine) are added to the reaction flask, the obtained mixture isheated up to 280° C. and reacted for 30 minutes. When the reaction iscomplete, the reaction solution is rapidly cooled down to momtemperature to obtain a reactant including the (red-light emitting)InP/ZnS or (green light emitting) InZnP/ZnS semiconductor nanocrystal.

(2) An excessive amount of ethanol is added to the reactant includingthe InP/ZnS semiconductor nanocrystal, and the mixture is centrifuged.After the centrifuging, a supernatant is removed, and a precipitatetherein is dried and dispersed in chloroform or toluene to obtain aquantum dot solution (hereinafter, a QD solution). A UV-vis absorptionspectrum of the QD solution is measured. The quantum dot had a quantumefficiency of greater than or equal to 50% (50% to 100%).

Example 1

[1] Preparation of Quantum Dot-Binder Dispersion

A chloroform dispersion of the quantum dots (InP/ZnS core-shell, greenlight emitting) including oleic acid as a hydrophobic organic ligand ona surface thereof synthesized in Reference Example 1 is prepared. Thechloroform dispersion including 50 grams (g) of the quantum dots ismixed with 100 g of a binder (a four-membered copolymer of methacrylicacid, benzyl methacrylate, hydroxyethylmethacrylate, and styrene (a moleratio=61.5%:12%:16.3%:10.2%), an acid value: 130 mg KOH/g, a numberaverage molecular weight 8000 g/mol) solution (solvent: polypropyleneglycol monomethyl ether acetate having a concentration of 30 wt %) toprepare a quantum dot-binder dispersion. It is confirmed that thequantum dots are uniformly dispersed in the prepared quantum dot-binderdispersion.

[2] Preparation of Photosensitive Composition

To the quantum dot-binder dispersion prepared in [1], 100 g ofhexaacrylate having the following structure as a photopolymerizablemonomer, an oximeester compound as an initiator, 30 g of TiO₂ as a lightdiffusing agent (an average particle size: 200 nm), and 300 g ofpropylene glycol methyl ether acetate (“PGMEA”) as a solvent is added toobtain a photosensitive composition.

It is confirmed that the prepared composition may form dispersionwithout showing any noticeable agglomeration due to the addition of thequantum dots.

[3] Formation of Quantum Dot-Polymer Composite Pattern

The photosensitive composition obtained from [2] is spin-coated on aglass substrate at 150 rpm for 5 seconds to provide a film. The obtainedfilm is pre-baked (“PRB”) at 100° C. A blue photoconversion efficiencyof the pre-baked film is measured, and the results are compiled inTable 1. The pre-baked film is radiated by light (a wavelength: 365 nm,intensity: 100 millijoule (mJ)) for 1 second under a mask having apredetermined pattern (e.g., a square dot or stripe pattern) anddeveloped by a potassium hydroxide aqueous solution (a concentration:0.043%) for 50 seconds to provide a quantum dot-polymer compositepattern.

[4] Formation of Capping Layer and POB Treatment

The pattern is subjected to an inter POB heat treatment at 140° C. for10 minutes to measure a blue photoconversion efficiency. The results arecompiled in Table 1.

On the inter POB heat-treated pattern, a capping layer (a thickness: 400nm) including titanium dioxide is formed through sputtering (sputteringtemperature: room temperature, sputtering gas: argon+oxygen, target:titanium metal, purity: 99.999%), then, its blue photoconversionefficiency is measured again, and the results are compiled in Table 1.

The layered structure including the capping layer is POB heat treated at180° C. for 30 minutes, and then, its blue photoconversion efficiency ismeasured. Subsequently, the layered structure is radiated by excitedlight having a wavelength of 449 nm at 65° C. under relative humidity of85% for 24 hours (an aging treatment).

The results are compiled in Table 1.

Comparative Example 1

The quantum dot polymer composite pattern manufactured in the samemethod as Example 1 is POB heat treated at 180° C. for 30 minuteswithout performing the inter POB heat treatment and forming the cappinglayer. A blue photoconversion efficiency of the pattern is measured, andthe results are shown in Table 1.

TABLE 1 Photoconversion Maintenance Process efficiency (%) ratio (%)Example 1 PRB 32.4% 100% Inter POB at 140° C. 26.8%  83% Formation ofTiO₂ layer 31.4%  97% After POB 31.9%  99% Aging 34.5% 107% ComparativeAfter POB 27.2%  84% Example 1

Referring to Table 1, the layered structure of Example exhibited almostno light characteristic deterioration due to a heat treatment, but thepattern of Comparative Example 1 exhibited substantial lightcharacteristic deterioration due to the heat treatment.

Example 2

A quantum dot-polymer composite pattern is obtained according to thesame method as Example 1 except for using a chloroform dispersion ofquantum dots (InP/ZnS core-shell, red light emitting) including oleicacid as a hydrophobic organic ligand on the surface. The pattern isinter POB heat treated at 140° C. for 30 minutes, and its bluephotoconversion efficiency is measured. The results are compiled inTable 2. A capping layer (thickness: 400 nm) is formed on the inter POBheat treated pattern in the same method as Example 1, and its bluephotoconversion efficiency is measured.

The layered structure having the capping layer is POB heat treated at180° C. for 30 minutes, and its blue photoconversion efficiency ismeasured. Then, the layered structure is radiated by excited lighthaving a wavelength of 449 nm at 65° C. under relative humidity of 85%for 24 hours (an aging treatment). The results are shown in Table 2.

Comparative Example 2

A quantum dot polymer composite pattern formed in the same method asExample 2 is POB heat treated at 180° C. for 30 minutes withoutperforming the inter POB heat treatment and forming the capping layer. A(blue) photoconversion efficiency of the pattern is measured, and theresults are compiled in Table 2.

TABLE 2 Photoconversion Maintenance Process efficiency (%) ratio (%)Example 2 PRB 30.8% 100% inter POB at 140° C. 23.8%  77% Formation ofTiO₂ layer 27.8%  90% After POB 28.8%  93% Aging 30.2%  98% ComparativeAfter POB 21.2%  69% Example 2

Referring to the results of Table 2, the layered structure of Example 2exhibited almost no light characteristic deterioration due to a heattreatment, but the pattern of Comparative Example 2 exhibitedsubstantial light characteristic deterioration due to the heattreatment.

Example 3

A quantum dot-polymer composite pattern is obtained according to thesame method as Example 1 except for using 60 g of quantum dots (InP/ZnScore-shell, green light emitting) including oleic acid as a hydrophobicorganic ligand on the surface. For each of the quantum dot-polymercomposite patterns after pre-baking and light exposure & development,blue light photoconversion efficiency is measured. A TiO₂-containingcapping layer (thickness: 400 nm) is formed on the pattern in the samemethod as Example 1 and then, post-baked at 180° C. for 30 minutes. Ablue photoconversion efficiency of the layered structure is measured.

A polymer solution including urethane acrylate is spin-coated to form anovercoat layer on the TiO₂-containing capping layer of the layeredstructure (CAP). The layered structure including the overcoat layer isheat-treated at 230° C. for 30 minutes and subsequently, radiated byexcited light having a wavelength of 449 nm for 24 hours at 65° C. underrelative humidity of 85% (aging treatment). A blue photoconversionefficiency of the layered structure after the heat treatment at 230° C.and the aging treatment is measured. The blue photoconversionefficiencies measured in each step are compiled in a graph of FIG. 6 .

Comparative Example 3

A layered structure is formed in the same method as Example 3 without acapping layer, and its blue photoconversion efficiencies in each stepare compiled in a graph of FIG. 6 .

The results of FIG. 6 suggest the following: the capping layer in thelayered structure of Example 3 may suppress light emittingcharacteristic deterioration of a photoluminescent layer due to acontact of quantum dots with other layers (e.g., a planarizationlayer/an alignment layer included in a liquid crystal display) as wellas prevent quantum dot photoluminescence characteristic deteriorationdue to a heat treatment.

Example 4

A quantum dot-polymer composite pattern is obtained according to thesame method as Example 1 except for using 60 g of quantum dots (InP/ZnScore-shell, red light emitting) including oleic acid as a hydrophobicorganic ligand on the surface. For each of the quantum dot-polymercomposite patterns after pre-baking and light exposure and development,blue light photoconversion efficiency is measured. A TiO₂-containingcapping layer (thickness: 400 nm) is formed on the pattern according tothe same method as Example 1 and then, post-baked at 180° C. for 30minutes. A blue photoconversion efficiency of the obtained layeredstructure is measured.

On the TiO₂-containing capping layer of the layered structure, anurethaneacrylate polymer solution is spin-coated to form an overcoatlayer.

The layered structure including the overcoat layer is heat-treated at230° C. for 30 minutes and subsequently, radiated by excited lighthaving a wavelength of 449 nm at 65° C. under relative humidity of 85%for 24 hours (aging treatment). A blue photoconversion efficiency of thelayered structure after the heat treatment at 230° C. and the agingtreatment is measured. The blue photoconversion efficiencies in eachstep are compiled in a graph of FIG. 7 .

Comparative Example 4

A layered structure is formed according to the same method as Example 4without forming a capping layer, and its blue photoconversionefficiencies in each step are compiled in a graph of FIG. 7 .

The results of FIG. 7 suggest the following: the capping layer in thelayered structure of Example 4 may suppress light emittingcharacteristic deterioration of a photoluminescent layer due to acontact of quantum dots with other layers (e.g., a planarizationlayer/an alignment layer included in a liquid crystal display) as wellas prevent quantum dot photoluminescence characteristic deteriorationdue to a heat treatment.

While this disclosure has been described in connection with what ispresently considered to be practical example embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A layered structure comprising: a transparentsubstrate disposed on a surface of a photoluminescent layer comprising apattern of a quantum dot polymer composite; a capping layer directlydisposed on an opposite surface of the photoluminescent layer, whereinthe capping layer comprises at least two adjacent layers including afirst layer in contact with the photoluminescent layer and comprising afirst inorganic material having a first refractive index, and a secondlayer comprising a second inorganic material and having a secondrefractive index, wherein the second layer directly contacts the firstlayer, and the first refractive index is lower than the secondrefractive index, and the capping layer has a transmittance of greaterthan or equal to about 90% for light having a wavelength of about 380nanometers to about 520 nanometers; and an overcoat disposed on thecapping layer, the overcoat comprising an organic polymer, wherein thequantum dot polymer composite comprises a polymer matrix, and aplurality of quantum dots in the polymer matrix, wherein the pattern ofthe quantum dot polymer composite comprises a repeating section andwherein the repeating section comprises a first section configured toemit light of a first peak wavelength, and wherein each of the first andthe second inorganic material comprises a metal oxide, a metal nitride,a metal oxynitride, a metal sulfide, or a combination thereof.
 2. Thelayered structure of claim 1, wherein the polymer matrix comprises across-linked polymer and a linear polymer comprising a carboxylic acidgroup-containing repeating unit.
 3. The layered structure of claim 2,wherein the cross-linked polymer comprises a thiol-ene resin, across-linked poly(meth)acrylate, a cross-linked polyurethane, across-linked epoxy resin, a cross-linked vinyl polymer, a cross-linkedsilicone resin, or a combination thereof.
 4. The layered structure ofclaim 2, wherein the carboxylic acid group-containing repeating unit isderived from a monomer comprising a carboxylic acid group and acarbon-carbon double bond, a monomer comprising a dianhydride moiety, ora combination thereof.
 5. The layered structure of claim 1, wherein theplurality of quantum dots comprises a Group II-VI compound, a GroupIII-V compound, a Group IV-VI compound, a Group IV element or acompound, a Group I-III-VI compound, a Group I-II-IV-VI compound, or acombination thereof.
 6. The layered structure of claim 1, wherein theplurality of quantum dots does not comprise cadmium.
 7. The layeredstructure of claim 1, wherein the plurality of quantum dots comprises acore-shell structure.
 8. The layered structure of claim 1, wherein theplurality of quantum dots comprise an organic ligand on a thereof,wherein the organic ligand comprises RCOOH, RNH₂, R₂NH, R₃N, RSH, R₃PO,R₃P, ROH, RCOOR′, RPO(OH)₂, R₂POOH, wherein R and R′ are eachindependently a C5 to C24 substituted or unsubstituted aliphatichydrocarbon group, or a C6 to C20 substituted or unsubstituted aromatichydrocarbon group, a polymeric organic ligand, or a combination thereof.9. The layered structure of claim 1, wherein the repeating sectionfurther comprises a second section configured to emit light of a secondpeak wavelength that is different from the first peak wavelength; and athird section configured to emit or transmit light of a third peakwavelength that is different from the first peak wavelength and thesecond peak wavelength.
 10. The layered structure of claim 9, whereinthe first peak wavelength is greater than about 580 nanometers and lessthan or equal to about 680 nanometers, the second peak wavelength isgreater than about 480 nanometers and less than or equal to about 580nanometers, and the third peak wavelength is greater than or equal toabout 380 nanometers and less than or equal to about 480 nanometers. 11.The layered structure of claim 1, wherein the second inorganic materialis titanium oxide or zirconium oxide.
 12. The layered structure of claim1, wherein each of the first and the second inorganic material has arefractive index of about 1.4 to about
 3. 13. The layered structure ofclaim 1, wherein the first inorganic material comprises a silicon oxide,and the second inorganic material comprises a hafnium oxide, a tantalumoxide, a titanium oxide, a zirconium oxide, a zinc oxide, a zincsulfide, a magnesium oxide, a cesium oxide, a lanthanum oxide, an indiumoxide, a niobium oxide, an aluminum oxide, or a combination thereof. 14.The layered structure of claim 1, wherein at least one of the firstlayer or the second layer of the capping layer comprises a continuousfilm of the first inorganic material or the second inorganic material.15. The layered structure of claim 1, wherein the at least two adjacentlayers of the capping layer have a different thickness, a differenttransmittance, or a combination thereof.
 16. The layered structure ofclaim 1, wherein a thickness of the capping layer is greater than orequal to about 100 nanometers and less than or equal to about 10000nanometers.
 17. The layered structure of claim 1, wherein the pluralityof quantum dot have a core-shell structure and comprises a Group II-VIcompound, a Group III-V compound, a Group IV-VI compound, a Group IVelement or a compound, a Group I-III-VI compound, a Group I-II-IV-VIcompound, or a combination thereof, and do not comprise cadmium, and therepeating section further comprises a second section configured to emitlight of a second peak wavelength that is different from the first peakwavelength; and a third section configured to emit or transmit light ofa third peak wavelength that is different from the first peak wavelengthand the second peak wavelength.
 18. The layered structure of claim 17,wherein the first inorganic material comprises a silicon oxide and thesecond inorganic material is titanium oxide or zirconium oxide.
 19. Amethod of producing the layered structure of claim 1, the methodcomprising: applying a composition comprising the plurality of quantumdots, a photopolymerizable monomer comprising at least two polymerizablemoieties, a linear polymer comprising a carboxylic acid group-containingrepeating unit, a photoinitiator, and an organic solvent, on thetransparent substrate to form a film; exposing a predetermined region ofthe formed film to light to polymerize and cross-link in the exposedpredetermined region and to form the quantum dot polymer composite withthe plurality of the quantum dots being dispersed in the polymer matrix;removing an unexposed region from the film using an alkali aqueoussolution to obtain the pattern of the quantum dot-polymer composite;forming the capping layer directly on the pattern of the quantumdot-polymer composite; and forming the overcoat on the capping layer.20. The method of claim 19, wherein the method further comprises heatingthe exposed predetermined region at a temperature of greater than orequal to the organic solvent's boiling point—10° C. and less than about160° C. before forming the capping layer.
 21. The method of claim 19,wherein the forming of the capping layer comprises using physical vapordeposition, chemical vapor deposition, or a combination thereof.
 22. Anelectronic device comprising: a panel comprising a light source; and aphotoluminescent color filter comprising the layered structure of claim1, wherein the photoluminescent color filter is disposed on the panel.